The microbiology of post-cesarean wound morbidity

Objective: To determine the microbiology of wound morbidity following cesarean deliveries. Methods: Nine hundred thirty-nine wounds in postcesarean patients were followed prospectively. Aspirates from the abdominal incision were collected if the wounds developed erythema, induration, or pain and had demonstrable fluid collection noted on ultrasound. Cultures were also obtained of wound exudates when there was spontaneous separation of the skin. Gram stains were performed concomitantly with culture. Results: The cumulative incidence of post-cesarean wound morbidity between September 1990 and June 1991 was 6.9% (65 of 939), and the rate of culture-positive wounds was 72% (47 of 65). Ureaplasma urealyticum was the most frequent isolate at a rate of 62% (29 of 47), followed by coagulase-negative staphylococci at 32% (15 of 47) and Enterococcus faecalis at 28% (13 of 47). Gram stains of the exudates obtained were used to predict microbiologic results. Organisms present on Gram stain yielded a sensitivity of 0.55, specificity of 1.0, positive predictive value of 1.0, and negative predictive value of 0.71 when used to predict positive culture results for bacterial wound infection other than with genital mycoplasmas. White blood cell counts greater than ten per 400´ high-power fields yielded a sensitivity of 0.83, specificity of 0.72, positive predictive value of 0.89, and negative predictive value of 0.62 when used to predict wound infection including genital mycoplasmas. Conclusions: Genital mycoplasmas are the most prevalent bacterium in post-cesarean wound infections in this population. If genital mycoplasmas are pathogenic in this setting, then the Gram stain may be useful in predicting wound microbiology. More research is needed on the pathogenic role of genital mycoplasmas in wound infections.